青藏高原东北部祁连圆柏树木年轮学研究中的年龄与个体生长问题

树木年轮的生长与气候因子、立地环境条件以及树木自身生长节律等密切相关。一方面，干旱半干旱区的树木年轮宽窄能够比较真实地记录过去的气候变化，据此，可以利用树木年轮资料重建干旱半干旱区过去几百年甚至上千年的气候变化。另一方面，立地环境条件也可能改变年轮生长与气候因子之间的响应关系。 有“世界屋脊”之称的青藏高原地区的气候变化与亚洲季风及全球气候系统密切相关。青藏高原也是世界上地形最复杂的高原，具有极其复杂的地形、地貌。因此，在青藏高原尤其是其东北部的干旱半干旱区开展树木年轮气候学及生态学研究具有极其重要的意义。本研究的目标就是利用树木年轮生态学方法研究树龄、立地条件等对青藏高原东北部祁连圆柏树木年轮宽度生长的可能影响。 为实现以上目标，本研究拟订了以下主要研究内容：探究祁连圆柏树种的年轮宽度生长对气候的响应关系中的年龄问题;比较每个样方内的个体径向生长变化以及三个样方内祁连圆柏个体径向生长规律;探讨导致个体径向生长差异的可能原因。 本文的研究材料为青藏高原常见的长寿树种祁连圆柏，研究方法是国际上通用的树木年轮学研究方法和手段。主要结果归纳如下： 1）依据国际树木年轮库的标准，建立了青藏高原东北部包括德令哈、乌兰、香日德、油葫芦、青羊沟、芒扎、东沟七个采样点的树木年轮年表。 2）运用响应函数、相关函数及单因素方差分析等方法分析了年龄因素对树木年轮生长与气候关系的可能影响。结果为：年龄在200-500年之间的祁连圆柏径向生长对气候变化的响应关系比较好。幼树对气候变化的响应相对差。而当树龄大于500年时，尽管由于树木内部生理变化，对气候变化的响应相对减弱，但是单因素方差分析结果显示这种减弱未能达到显著水平。因此，总体而言，我们认为长寿的祁连圆柏树种是重建古气候的理想材料。 3）通过设立样方，分析了样方内个体径向生长之间的相关性和差异性，以及生长释放与抑制事件发生的规律。同时还探讨了树间距离、立地微环境、限制性气候因子等对树木年轮生长的可能影响。主要研究结果：青藏高原东北部祁连圆柏年轮宽度序列中生长抑制事件发生的频率相对生长释放事件低很多，且存在个体间的差异;不同样方内个体径向生长之间的相关性有差别，乌兰样方内单棵树年轮宽度指数序列之间的相关性比香日德样方以及德令哈样方内单棵树年轮宽度指数序列之间的相关性差;乌兰样方内树木年轮生长受立地微环境的影响比较大。 本论文中年龄相关的树木年轮生长与气候因子响应关系的研究进一步证实了祁连圆柏在重建古气候方面的应用价值;通过设立样方进行祁连圆柏种群内个体差异及立地条件对比方面的研究结果对重建青藏高原地区的气候变化、了解采样地的干扰历史以及树木年轮采样工作等也同样具有重要的参考意义。

增温与土地利用变化对青藏高原高寒草甸生态系统温室气体通量影响的研究

随着青藏高原气候变暖进程及放牧压力与开垦面积的逐年加大，非常有必要评价青藏高原高寒草甸生态系统温室气体通量对气候变暖、放牧（包括粪尿斑）和开垦的响应和反馈。与此同时，我们进行了粪尿斑及开垦对土壤理化性质影响研究。本研究对于青藏高原高寒草甸C、N循环关键过程对全球变化响应的认识具有重要意义。 本文通过2年（2006-2007）增温（白天+1.2℃，晚上+1.7℃）与放牧耦合试验，在生长季观测了增温与放牧对高寒草甸生态系统温室气体通量的影响。研究初步表明，增温试验显著增加10 cm土壤温度1℃左右；在放牧频度相对较高的2007年，放牧也显著增加了土壤温度1℃左右。总体上，增温对土壤湿度的影响不显著。 增温可以促进土壤对CH4的吸收，而放牧对CH4通量影响不大或起到一定程度抑制作用。在较低放牧频度的2006年，放牧显著降低了植物-土壤系统CO2总释放量，增温促进了CO2的释放。而在放牧频度相对较高的2007年生长季，没有发现增温及放牧对土壤-植被系统CO2释放显著的影响。2006年放牧后，增温促进了高寒草甸土壤N2O的释放；2007年，增温不放牧小区N2O总通量较对照增加了24.6%，同时放牧处理也促进了N2O释放。基于土壤温度和土壤湿度的线性回归模型可以解释55%-89%的CH4通量变异，而土壤湿度较土壤温度对CH4通量影响更大。土壤温度是影响CO2和N2O通量的主要因子，通过拟合的指数型曲线，土壤温度可以分别解释43%-63%CO2通量变异与65%-81%N2O通量变异。 在2005年与2006年夏季放牧期间，对牦牛粪尿斑处理对高寒草甸CH4、CO2和N2O通量进行了观测。牛粪小区2年观测期内CH4平均通量为687 μg m-2 h-1，而尿斑和对照土壤吸收CH4（平均通量分别为-34 μg m-2 h-1和-39 μg m-2 h-1）。牛粪小区CO2在2005年和2006年观测期内累积释放量较对照分别增加了35.8%和49.7%，而牛尿小区与对照累积释放量差异不显著。牛尿与牛粪小区N2O累积释放量显著高于对照，在2005年牛尿与牛粪小区N2O累积释放量较对照分别增加了3.7和3.5倍，而在2006年分别增加了2.1和1.8倍。因此，在估算放牧高寒草甸生态系统N2O释放时，来自牛粪斑释放量是不能被忽略的。但在中等放牧强度下（1.45头ha-1 y-1），有粪尿斑覆盖的高寒草甸在观测期内全球变暖潜势较相同面积没有粪尿斑覆盖的草甸仅增加了1%。土壤水分孔隙度（WFPS）可以解释牛尿小区35%和对照小区36%CH4通量变异。土壤温度是控制CO2释放的主要因子之一，它可以解释所有处理40-75% CO2的变异。牛尿处理（34%）、牛粪处理（48%）及对照（56%）N2O时间变异则同时受土壤温度和WFPS的驱动。在观测期内，牛尿可以显著提高土壤的pH值。粪尿斑对土壤微生物量碳氮没有产生显著性影响，但在一定时段内能显著增加土壤无机氮含量。 通过在青藏高原高寒草甸开展的人工草地试验，初步探讨了不同土地利用方式（种植燕麦、开垦后闲置及自然恢复）对CO2、CH4和N2O通量，以及土壤无机氮和微生物量氮的影响。燕麦地、自然恢复草地及开垦闲置地与天然草地相比，吸收CH4的能力均表现为增强（CH4的吸收总量分别增加了31.9%、57.2%和71.0%）。由于燕麦地生物量低于天然草地与恢复草地，造成了燕麦地土壤-植被CO2释放量低于天然草地和恢复草地。而闲置地几乎没有植被覆盖，其CO2释放量显著低于天然草地。草地恢复8年后，CO2释放基本恢复到天然草地的水平。闲置地N2O总通量显著高于天然草地，较天然草地增加了60.5%。观测期内燕麦地与天然草地相比，N2O总通量增加了24.3%，但没有达到显著性水平。开垦及种植燕麦，增加了土壤硝态氮的含量，而自然恢复地、燕麦地、天然草地和闲置地在观测期内土壤铵态氮平均含量没有观察到显著性差异。燕麦地土壤微生物量氮平均含量最低（119.7 mg N kg-1），而自然恢复草地、天然草地和闲置地土壤微生物量氮差异不大。

Y chromosome haplotypes reveal prehistorical migrations to the Himalayas

By using 19 Y chromosome biallelic markers and 3 Y chromosome microsatellite markers, we analyzed the genetic structure of 31 indigenous Sino-Tibetan speaking populations (607 individuals) currently residing in East, Southeast, and South Asia. Our results showed that a T to C mutation at locus M122 is highly prevalent in almost all of the Sino-Tibetan populations, implying a strong genetic affinity among populations in the same language family. Furthermore, the extremely high frequency of H8, a haplotype derived from M122C, in the Sino-Tibetan speaking populations in the Himalayas including Tibet and northeast India indicated a strong bottleneck effect that occurred during a westward and then southward migration of the founding population of Tibeto-Burmans. We, therefore, postulate that the ancient people, who lived in the upper-middle Yellow River basin about 10,000 years ago and developed one of the earliest Neolithic cultures in East Asia, were the ancestors of modem Sino-Tibetan populations.

Assessment of cattle genetic introgression into domestic yak populations using mitochondrial and microsatellite DNA markers

Hybridization between yak Poephagus grunniens and taurine Bos taurus or indicine B. indicus cattle has been widely practiced throughout the yak geographical range, and gene flow is expected to have occurred between these species. To assess the impact of cattle admixture on domestic yak, we examined 1076 domestic yak from 29 populations collected in China, Bhutan, Nepal, India, Pakistan, Kyrgyzstan, Mongolia and Russia using mitochondrial DNA and 17 autosomal microsatellite loci. A cattle diagnostic marker-based analysis reveals cattle-specific mtDNA and/or autosomal microsatellite allele introgression in 127 yak individuals from 22 populations. The mean level of cattle admixture across the populations, calculated using allelic information at 17 autosomal microsatellite loci, remains relatively low (mY(cattle) = 2.66 +/- 0.53% and Q(cattle) = 0.69 +/- 2.58%), although it varies a lot across populations as well as among individuals within population. Although the level of cattle admixture shows a clear geographical structure, with higher levels of admixture in the Qinghai-Tibetan Plateau and Mongolian and Russian regions, and lower levels in the Himalayan and Pamir Plateau region, our results indicate that the level of cattle admixture is not significantly correlated with the altitude across geographical regions as well as within geographical region. Although yak-cattle hybridization is primarily driven to produce F-1 hybrids, our results show that the subsequent gene flow between yak and cattle took place and has affected contemporary genetic make-up of domestic yak. To protect yak genetic integrity, hybridization between yak and cattle should be tightly controlled.

The ADH1B Arg47His polymorphism in East Asian populations and expansion of rice domestication in history

Background: The emergence of agriculture about 10,000 years ago marks a dramatic change in human evolutionary history. The diet shift in agriculture societies might have a great impact on the genetic makeup of Neolithic human populations. The regionally restricted enrichment of the class I alcohol dehydrogenase sequence polymorphism (ADH1BArg47His) in southern China and the adjacent areas suggests Darwinian positive selection on this genetic locus during Neolithic time though the driving force is yet to be disclosed. Results: We studied a total of 38 populations (2,275 individuals) including Han Chinese, Tibetan and other ethnic populations across China. The geographic distribution of the ADH1B*47His allele in these populations indicates a clear east-to-west cline, and it is dominant in south-eastern populations but rare in Tibetan populations. The molecular dating suggests that the emergence of the ADH1B*47His allele occurred about 10,000 similar to 7,000 years ago. Conclusion: We present genetic evidence of selection on the ADH1BArg47His polymorphism caused by the emergence and expansion of rice domestication in East Asia. The geographic distribution of the ADH1B*47His allele in East Asia is consistent with the unearthed culture relic sites of rice domestication in China. The estimated origin time of ADH1B*47His allele in those populations coincides with the time of origin and expansion of Neolithic agriculture in southern China.

Phylogenetic study of complete cytochrome b genes in musk deer (genus Moschus) using museum samples

As an endangered animal group, musk deer (genus Moschus) are not only a great concern of wildlife conservation, but also of special interest to evolutionary studies due to long-standing arguments on the taxonomic and phylogenetic associations in this group. Using museum samples, we sequenced complete mitochondrial cytochrome b genes (1140 bp) of all suggested species of musk deer in order to reconstruct their phylogenetic history through molecular information. Our results showed that the cytochrome b gene tree is rather robust and concurred for all the algorithms employed (parsimony, maximum likelihood, and distance methods). Further, the relative rate test indicated a constant sequence substitution rate among all the species, permitting the dating of divergence events by molecular clock. According to the molecular topology, M. moschiferus branched off the earliest from a common ancestor of musk deer (about 700,000 years ago); then followed the bifurcation forming the M. berezouskii lineage and the lineage clustering M. fuscus, M. chrysogaster, and M. leucogaster (around 370,000 years before present), interestingly the most recent speciation event in musk deer happened rather recently (140,000 years ago), which might have resulted from the diversified habitats and geographic barriers in southwest China caused by gigantic movements of the Qinghai-Tibetan Plateau in history. Combining the data of current distributions, fossil records, and molecular data of this study, we suggest that the historical dispersion of musk deer might be from north to south in China. Additionally, in our further analyses involving other pecora species, musk deer was strongly supported as a monophyletic group and a valid family in Artiodactyla, closely related to Cervidae. (C) 1999 Academic Press.

Cytogenetics, morphology and evolution of four subspecies of the Giant Sheep argali (Ovis ammon) of Asia

Dalai-lamae (Ovis ammon dalai-lamae), Gobi (O. a. darwini), Kara Tau (O. a. nigrimontana) and Tibetan (O. a. hodgsoni) argali share a 2n = 56 diploid chromosome number and a karyotype consisting of 2 pairs of biarmed and 25 pairs of acrocentric autosomes, a large acrocentric X and a minute Y chromosome. The Giemsa-banding patterns of the largest pair of biarmed chromosomes were identical to those of the largest biarmed chromosomes in all wild sheep and domestic sheep of the genus Ovis. The banding patterns of the second pair of biarmed chromosomes (metacentric) were identical to the third pair of biarmed chromosomes in Ovis with 2n = 54 and to the third largest pair of chromosomes in the 2n = 52 karyotype of Siberian snow sheep (O. nivicola). The G-banded karyotypes of dalai-lamae, darwini, hodgsoni and nigrimontana are consistent with all subspecies of argali (O. ammon), except that the Y chromosome is acrocentric instead of metacentric as typical of the argaliform wild sheep and Ovis. The Dalai-lamae and Tibetan argali specimens exhibit the light-colored, long-haired ruffs and body coloration typical of argalis from the Tibetan Plateau. The Gobi argali, from the extreme western Gobi, is similar to the dark phase argali.

Melanocortin-1 receptor gene variants in four Chinese ethnic populations

There is strong relationship between melanocortin-1 receptor (MC1R) gene variants and human hair color and skin type. Based on a sequencing study of MC1R gene in 50 individuals from the Uygur, Tibetan, Wa and Dai ethnic populations, we discuss the occurre

Phylogeographic analysis of mtDNA variation in four ethnic populations from Yunnan Province: new data and a reappraisal

Two sets of mitochondrial DNA (mtDNA) hypervariable segment I (HVS-I) data from four ethnic populations (Tibetan, Va, Dai, and Lahu) from Yunnan Province, China, were analyzed here by using phylogeographic methods. The results suggest that more attention

Molecular phylogeny and biogeography of Oriental voles: genus Eothenomys (Muridae, Mammalia)

Oriental voles of the genus Eothenomys are predominantly distributed along the Southeastern shoulder of the Qinghai-Tibetan Plateau. Based on phylogenetic analyses of the mitochondrial cytochrome b gene (1143 bp) obtained from 23 specimens (eight species)

Phylogenetic relationships in genus Niviventer (Rodentia : Muridae) in China inferred from complete mitochondrial cytochrome b gene

Chinese species of the genus Niviventer, predominantly distributed in the southeastern Tibetan Plateau and in Taiwan, are a diverse group and have not yet received a thorough molecular phylogenetic analysis. Here, we reconstructed the phylogenetic relatio

SOCIAL-DEVELOPMENT OF INFANTS OF MACACA-THIBETANA AT MOUNT-EMEI, CHINA

The development of infant Macaca thibetana was studied at Mount Emei, China, and compared to that of other macaque species. It was found that there are many common features in the process of infant socialization in species of the genus Macaca: mothers play an important and active role, other group members influence the infants' development to a greater or lesser extent and play is a major activity in the life of infants. Some differences were found to exist, however, between macaque species. These included differences in maternal care behaviour such as 'len', leaving time and weaning time. Paternal behaviours were also found to vary within and among species. Tibetan macaque males care for infants extensively, and they may use infants as an agonistic buffer. The natural and social environment may also influence differences between macaque species in infant development.

EARLY MOTHER-INFANT RELATIONSHIPS OF MACACA-THIBETANA AT MT-EMEI CHINA

Quantitative data on early mother-infant relationships in the Tibetan macaque was collected during the first 23 weeks of infant life in spring, 1987, at Mt. Emei, China. During the first week of life, infants spent 98.3% of their time in ventroventral contact with their mothers. This contact rapidly decreased to 33.8% by the 4th week and thereafter to 0.85% by the 23rd week. Nipple contact decreased relatively slowly from 89.7% to 62.9% within the first 4 weeks of infant life and to 19.8% by the 23rd week. Ventrolateral and ventrodorsal contact appeared by the 2nd week, mean-while, maternal restraining behavior appeared, and reached a peak by the 3rd week. The mother neither encouraged nor discouraged her infant's independence during 4-8th weeks. Maternal rejection of the infant was first observed when the infant was 11 weeks old and continued thereafter.

藏鸡线粒体全基因组序列的测定和分析

通过PCR扩增,测序,拼接,获得藏鸡(Tibetan Chicken)线粒体全基因组序列并进行数据分析处理.藏鸡线粒体全基因组序列全长16 783 bp,共有13个蛋白质编码基因、2个rRNA基因、22个tRNA基因和1个D-loop区.模拟电子酶切结果显示,藏鸡Dra Ⅰ酶的酶切结果和先前报道的原鸡,茶花鸡,尼西鸡和大理漾濞黄鸡的酶切结果都不相同,为藏鸡特有.基于D-loop区全序列和13个蛋白质编码基因序列,采用N-J算法与原鸡属4个种,3个亚种和3个家鸡品系构建系统进化树:初步确定藏鸡起源于红原鸡,与家鸡中的来航鸡、白洛克鸡亲缘关系最近,但是藏鸡的进化与来航鸡、白洛克鸡这两个家鸡品系又显得相对独立.推测可能原因是藏鸡的祖先在进入高原以后处于相对封闭的环境,从而形成了独特群体遗传特性.

藏北色林错流域的水文特征

本文报道丁1997年和1998年夏季对藏北色林错等水体水文特征的考察情况结 果表明，色林错是一个大型深水湖泊，表层水温在下午4：30左右达到最高，清晨7：30左右时最 低浅水区域表层湖水在6月份的极端最高水温为2l 2℃．韫端最低水温为11 0℃，而H甲均水温 变幅仅5 6℃，其幅度大于在同一时段湖区内不同区域之间表层水温的变化色林错湖水的DH值 较高．为9 19 9 66；表层水的pH昼夜变化较小，仅O．15．最高值出现在凌晨．同时水体不同区域 及深度的pH值基本一致．其溶解氧变化在4．62—5 12mg／L，而且不同深度水层之间的变幅较小． 仅0 03—0 35mg／L；但其湖汉浆东如瑞溶解氧的昼夜变幅为4 58 5 59mg／I，；盐度的日变幅为 1 60％ 2 20％考察表明．藏北水体的盐分有一个从河流到湖泊、以及由流水向静水富集的趋 势；鱼类的分布与水体盐分的含母密切相关，即鱼类随着水体盐分的增加而消失，代之H嗜盐性卣 虫的出现及大量繁衍